textproduct: Albany

WHAT HAS CHANGED

Heat Advisory issued for Thu across the Hudson Valley from Albany south, S. Taconics and Litchfield CT. Another Heat Advisory has been issued for a much larger portion of the region (excluding some higher terrain areas). There is now a Slight Risk (level 2 of 5) for severe storms Thursday from around I-90 south, with a Marginal Risk (level 1 of 5) north.

KEY MESSAGES

1) Well above normal temperatures and increasing humidity levels will occur through Friday. Heat Index values will be high enough for an increased risk in heat related illnesses on Thursday in lower elevations from Albany south, and most of the region (excluding some higher elevations) on Friday.

2) There is a chance for thunderstorms each day today through Friday, mainly in the afternoon and evening hours. Some storms could be severe with damaging winds and large hail, especially Thursday and Friday. Storms will be also be capable of producing heavy downpours.

3) Additional showers and thunderstorms are possible on Sunday associated with another cold front.

DISCUSSION

KEY MESSAGE 1...

An anomalously warm airmass will be in place through Fri (850 mb temperature anomalies of +1 to +2 STDEV). Humidity levels will increase today, but temperatures will modestly warm into the mid 80s in lower elevations due to increasing clouds and the threat of showers/T-storms this afternoon, so heat indices will be < 90F.

More substantial heat and humidity builds on Thu, with sunshine expected into the afternoon, as a warm front lifts well north of the area. Highs in the upper 80s/lower 90s combined with dewpoints in the upper 60s to lower 70s will result in heat indices in the 95-98F range in the Hudson Valley from ALB south, the S. Taconics and Litchfield CT. A Heat Advisory has been issued for these areas.

An additional Heat Advisory has been issued for Fri, across a more expansive area including much of the region (except for the Adirondacks, NE Catskills, and higher terrain NE of Albany). Fri will be the peak of the heat/humidity. Highs in the lower/mid 90s with dewpoints remaining in the upper 60s to lower 70s will result in heat indices in the 95-102F range in the advisory area. The Heat Advisory could be expanded to some other areas if confidence increases prior to Fri. Slightly cooler, but much less humid conditions will filter in on Sat behind a cold front.

KEY MESSAGE 2...

Upper ridge axis moves east of the area today, as a short wave trough approaches from the west and moves eastward across the region. Best chances for showers/T-storms will be this afternoon when the better forcing arrives. The latest CAMs depict this scenario. SBCAPE from HREF reaches 500-1500 J/Kg, with the greatest values west of the Hudson Valley. This is where a Marginal Risk (level 1 of 5) of severe storms exists. 0-6 km shear still looks fairly weak, but does increase to 20-25 kt towards evening. Probability of severe storms appears to be low from the Hudson Valley east, with isolated damaging wind gusts across far western areas. As PWAT anomalies increase to +2 to +3 STDEV, slow-moving downpours with locally heavy rainfall could result in isolated Flash Flooding late afternoon into this evening.

On Thu, guidance has come into better agreement focusing a short wave disturbance across the southern half of the area during the afternoon to early evening. More significant instability is expected to build with HREF indicating SBCAPE of 1500-2000 J/Kg. There looks to be just enough shear ~25-30 kt to organize storms given sufficient forcing from the disturbance. There was enough confidence for the Storm Prediction Center(SPC) to increase to a Slight Risk (level 2 of 5) of severe storms from around I-90 south, with a Marginal Risk (level 1 of 5) north of I-90 where instability/forcing is less. Large hail and damaging winds would be the main threats.

With the very warm and humid air mass remaining in place and peaking on Fri, even more substantial CAPE of 2000-3000 J/Kg could develop ahead of a cold front approaching from the west. Deep layer shear may also increase late in the day as the cold front and leading edge of upper level height falls moves in. There is some uncertainty in the timing, but at this time it appears that T-storms develop late afternoon west of the Hudson Valley and spread east during the evening. This time range is still outside the CAMs window, so will have a better idea for timing, mode and magnitude over the next few days. For now, SPC has a Slight Risk (level 2 of 5) across much of the area. Will continue to monitor trends.

KEY MESSAGE 3...

Another cold front and short wave aloft are expected to move across the area in the Sunday afternoon to evening time frame. Depending on the exact timing, there could be some stronger T-storms that develop. Zonal westerly flow aloft looks to be quite strong, with deep layer wind shear of potentially 50+ kt this will need to be monitored. Should sufficient instability develop and timing of forcing lines up, strong to severe storms may occur. Cooler, near normal temperatures are expected in wake of the cold front for early next week.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

Through 12z Thursday...VFR conditions continue to prevail across all terminals this morning as clouds continue to stream into the region and lower ahead of an incoming frontal system and upper level trough. Favored flying conditions should remain in place throughout the morning before scattered showers and thunderstorms this afternoon threaten to force MVFR to potentially IFR conditions. Confidence still remains relatively low pertaining to the timing, locations, and resulting conditions of showers and thunderstorms this afternoon, so maintained PROB30s throughout the TAFs to highlight the areas of greatest probability. MVFR ceilings and visibilities were maintained within these PROB30s until confidence increases and additional details can be provided with later updates. However, after convective activity ends late this evening, a gradual improvement to VFR conditions should occur.

Winds throughout the period will remain light with sustained speeds largely falling under 10 kt out of the south to southwest. However, within any thunderstorm that crosses a terminal, winds could get gusty with 15kt sustained and 25kt gusts.

Outlook...

Thursday Night: Moderate Operational Impact. Chance of SHRA. Friday: Moderate Operational Impact. Likely SHRA...TSRA. Friday Night: High Operational Impact. Likely SHRA...TSRA. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: Moderate Operational Impact. Breezy. Chance of SHRA...TSRA. Sunday Night: Moderate Operational Impact. Chance of SHRA. Monday: Low Operational Impact. Slight Chance of SHRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...Heat Advisory from noon to 8 PM EDT Thursday for CTZ001-013. Heat Advisory from noon to 8 PM EDT Friday for CTZ001-013. NY...Heat Advisory from noon to 8 PM EDT Thursday for NYZ049-052- 053-059-060-064>066. Heat Advisory from noon to 8 PM EDT Friday for NYZ038>041-043- 047>053-059>061-063>066-082>084. MA...Heat Advisory from noon to 8 PM EDT Friday for MAZ025. VT...None.